Many forms of flexible-walled containers have been proposed, including those shown in my patents noted above, having spouts for dispensing fluids. The containers are commonly formed of thermoplastic strip material, either two opposed strips or a single strip folded lengthwise. Seams are formed to define the outline of the body portion of the container and the dispensing spout.
The walls of a container become distended when the container is filled. The material used in making the container is efficiently used (from one point of view) where the shape of the container results in a large ratio of volume of the filled container to the surface area of the container walls. A square container (for example) has a relatively small ratio of volume to surface area because the material forming the corners cannot become greatly distended to contribute to the container volume in contrast (for example) to the extreme expansion of the central areas of the container walls. However, eliminating corners would ordinarily be accomplished by rounding the corners and consequently leaving the material outside those corners as scrap. Such scrap obviously does not contribute to the volume of the container.
It is often required that a container is to have a spout that projects from the main body portion of the container. Separately it is known (see my U.S. Pat. No. 3,815,794) that high stress concentrations tend to develop where the outline of a container includes a corner whose apex is directed inward, toward the interior of the container. The problem of efficient utilization of strip material in making containers is complicated by the requirements that the container is to include a projecting spout and that inward-directed corners are to be avoided.